Cell Aging and Death Essay

488 WordsApr 1, 20132 Pages
Cell Aging and Death Have you ever wondered why we age and die? What exactly is happening inside our bodies to bring on the wrinkles, gray hair, and the other changes seen in older people? We appear to age much like a car does: our parts start to wear out, and we gradually lose the ability to function. Aging is in part the result of accumulating damage to the molecules such as proteins, lipids, nucleic acids (DNA and RNA) that makes up our cells. Oxygen enter the lungs, passes into the tiny blood vessels that line them, gets into the creeks, rivers, and cascades of the bloodstream. Oxygen gets carried to every cell in every corner of the body. Once delivered to a cell, oxygen heads for the mitochondria, where it slurps up the electrons coming off the end of the energy production. Mitochondria need oxygen to generate cellular energy, and humans need a constant supply of that energy to survive. Oxygen has a darker side. Normally, an oxygen- molecule absorbs four electrons and is eventually safely converted into water. If an oxygen molecule only takes up one or two electrons, the result is one of a group of highly unstable molecules called reactive oxygen species that can damage many kinds of biological molecules by stilling their electrons. Many scientists speculate that another contributor to the aging process in the accumulation of cellular retirees. After cells divide about 50 times, they quit the hard work of dividing and enter a phase in which they no longer behave as they did in their youth. Each cell has 92 internal clocks, one at each end of its 46 chromosomes. Before a cell divides, it copies its chromosomes so that each daughter cell will get a complete set. Because of how the copying is done, the very ends of our long, slender chromosomes don't get copied. As a result, our chromosomes shorten with each cell division. The regions at the

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